Grooves are formed in the tread portion of a pneumatic tire to increase its wet performance. Though a large groove area ratio is vital to improving wet performance, if the groove area ratio is too large, the ground contact area may decrease, thus reducing the grip and steering stability of the tire.
To attempt to fulfill such competing requirements, a configuration including the width and number of circumferential grooves provided in the tread portion and the inclination angle and width of lug grooves has been devised (see, for example, Japanese Unexamined Patent Application Publication No. 2013-139241A).
However, if the ground contact area is increased to improve the steering stability of the pneumatic tire on dry road surfaces, the decreased groove area causes reduced drainage properties and steering stability on wet road surfaces. Alternatively, if the groove area is increased to improve drainage properties, the reduced ground contact area causes reduced steering stability on dry road surfaces.